Quantitative characterization of pore configuration in a porous Ni50.8 at.%-Ti SMA

A porous Ni50.8Ti49.2 shape memory alloy prepared by space holder assisted conventional sintering has been characterized via the micro-computed tomography (micro-CT). After proper image processing to remove the artifacts from the original reconstructed slices, the three-dimensional visualization, together with the size, shape and local structure of the pores have been obtained from the reconstructed volume. Primary pores with a volume fraction of 20.2% duplicate the size and morphology from the space holder particles and the space between the elemental nickel and titanium powders as raw materials, and segment the matrix into small volumes with an average diameter of around 220 mu m and a distance of around 125 mu m away from each other. This configuration in the porous Ni50.8Ti49.2 alloy can stall the propagation of martensite and lead to a gradual transformation. (C) 2015 The Authors. Published by Elsevier Ltd.